1. Field of the Invention
The present invention relates to grain spreaders for use with silos and more particularly relates to a grain spreader apparatus that is supported in the top of a silo and adapted to receive grain that is transmitted to the top of the silo from an external source. Even more particularly, the present invention relates to an improved grain spreader apparatus for use with silos wherein a housing includes a non-rotating and a rotating portion and wherein the plurality of chutes are supported for rotation with the rotating portion, each of the chutes being of a smaller transverse width starting with a larger width chute at the top and a smaller width chute at the bottom so that grain is discharged from one chute to the next by gravity and wherein a portion of the discharging grain falls to a lower chute and another portion of the grain falls freely to the silo floor.
2. General Background
Grain is stored in many different types of tanks, also known as silos or bins. One of the most popular is a vertically oriented cylindrical tank usually between twenty four and forty feet in diameter. The roof of such a tank is usually conical in shape, with a pitch of thirty to thirty five degrees (30.degree.-35.degree.). The roof is provided with an opening at the peak to provide for the intake of grain from a conveyor or conduit. This opening is typically part of a compression ring holding structural loads for the roof and other equipment and twenty to forty inches (20-40") in diameter for example.
Multiple tank arrangements are linear or circular in shape with overhead or inclined conveying devices used to load the material into the tanks. A single conveyor with one end anchored at the center point of several circularly oriented tanks is commonly used to load all the tanks in sequence.
Typically grain spreaders used to date are comprised of a gathering cone into which the flow of incoming grain is directed, located under the cone is some type of plate or trough which rotates to distribute the material about the center of the bin. Centrifugal type spreaders (eg. Domelson, U.S. Pat. No. 5,020,701 and Sukup, U.S. Pat. No. 3,966,124) distribute the grain by throwing it out from the center of the tank. They typically rotate one hundred to two hundred fifty RPM.
Trough type spreaders (Dixon, U.S. Pat. No. 4,902,185 and Wurdeman, U.S. Pat. No. 4,040,529) distribute the grain by means of troughs which extend from the center of the tank and typically rotate much slower (eg. 6 to 100 RPM).
Centrifugal type spreaders do not allow a homogeneous spread of material about the bin because the lighter material cannot be thrown as far as the heavier material. They tend to damage fragile grains from their aggressive rotation and because the individual grains impact the filled layer one at a time they tend to cause the fill to become closely packed.
Trough type spreaders tend to make a more homogeneous fill and the fill is lose if the grain is allowed to impact the filled layer in a stream rather than individual grains. They also do less damage to fragile grains because they rotate less aggressively.
Both types of spreaders are undependable at even distribution. The reason is the grain flow impacts the plate or trough at an angle to the vertical centerline. This angular flow is caused either by the conveying equipment not being perfectly centered or by the grain flowing to one side of the gathering cone. The momentum of the angular flowing grain forces more grain from the plate or trough at one point in its rotation. Likewise at an opposite point of rotation the grain tends to accumulate on the plate or trough. This causes an uneven distribution of material about the tank.